The Scotch Whisky Association (SWA), which is challenging the Scottish Government's plans for a 50p per unit minimum price for alcohol, insisted Mr Bot's opinion " encourages us in our long-held view that MUP is illegal".

Mr Bot said a European Union (EU) member state could only introduce such a policy if it demonstrates more advantages or fewer disadvantages than other alternatives - such as an increase in taxes.

He said the fact that increased taxation "is capable of procuring additional advantages by contributing to the general objective of combating alcohol abuse does not justify discarding that measure in favour of the MUP measure".

The Scottish Government, however, does not have the power to raise taxes on alcohol, with this ability reserved to Westminster.

Holyrood passed legislation to introduce minimum pricing in 2012 but t he policy stalled after the SWA and other European wine and spirits producers mounted a legal challenge, arguing that minimum pricing would breach European law.

The legal bid was initially rejected by judge Lord Doherty at the Court of Session in Edinburgh in 2013.

Following an appeal hearing, the case was referred to the Luxembourg court last year for its opinion on six points of European law, resulting in the publication of the new opinion.

European Court judges will now consider the matter and give their ruling later this year or early next year, with the case then going back to the Court of Session for a final decision.

Mr Bot said that, in his opinion, the policy of minimum pricing "meets the objective of combating alcohol abuse in a consistent and systematic manner".

He added: "The question that arises is whether the objective of protecting public health pursued by the Scottish authorities could not be attained in a less restrictive and equally effective manner by a fiscal measure.

"In other words, would a higher tax on alcoholic beverages enable the same objective to be attained as rules imposing a minimum price, while being less restrictive of trade?"

Mr Bot said it " is for those responsible for the drafting of those rules to show that increased taxation is not capable of meeting that targeted objective".

Ms Sturgeon said: " We welcome this opinion, in which the advocate general confirms that minimum unit pricing is not precluded by EU law, but sets out tests that the national court has to apply.

"Importantly, this initial opinion indicates it will be for the domestic courts to take a final decision on minimum unit pricing.

"The advocate general finds that the policy can be implemented if it is shown to be the most effective public-health measure available.

"As such, the legal process is ongoing and we await a final response from the European Court of Justice before the case returns to the Scottish courts."

She added: " While we must await the final outcome of this legal process, the Scottish Government remains certain that minimum unit pricing is the right measure for Scotland to reduce the harm that cheap, high-strength alcohol causes our communities.

"In recent weeks statistics have shown that alcohol-related deaths are rising again and that consumption may be rising again after a period of decline.

"We believe minimum unit pricing would save hundreds of lives in coming years and we will continue to vigorously make the case for this policy."

SWA chief executive David Frost said: " The opinion encourages us in our long-held view that MUP is illegal when there are less trade-restrictive measures available.

"We await the Court of Justice's final ruling.

" It remains important to address alcohol misuse with a range of other measures of proven effectiveness.

"We will continue to work closely with the Scottish Government and other stakeholders on this.

"There is a long-term trend of falling alcohol-related deaths and harms in Scotland which suggests that measures in place are working."

Doctors' leaders and health campaigners welcomed the opinion, with Alcohol Focus Scotland saying it " hopefully means we are one step closer to implementing minimum unit pricing in Scotland".

Acting deputy chief executive J ennifer Curran said: " Taxation alone simply cannot deliver the same benefits that minimum pricing can in raising the price of the cheapest alcohol that causes the most harm.

"More than 2,500 Scots have died because of alcohol since minimum pricing was passed by the Scottish Parliament in May 2012. In the last year we have seen a concerning rise in alcohol sales and deaths, underlining the need to implement minimum pricing as soon as possible.

"The cheapest, strongest alcohol is mainly bought by harmful drinkers and more than half of all the alcohol sold in supermarkets and off-sales is cheaper than 50p per unit. Evidence shows that a minimum unit price of 50p will protect health, cut crime and save lives."

Ms Curran hit out at the SWA for holding up the policy's implementation, saying: " By taking this legal action in the first place, the Scotch Whisky Association have undermined the collective view of the Scottish Parliament and they are costing taxpayers thousands of pounds in legal costs.

"It is quite clear that the multinational companies represented by the SWA prioritise their profits over people's lives."

Dr Peter Bennie, the chairman of the British Medical Association Scotland, stated: " We have been clear all along that minimum unit pricing is a public health policy that can reduce the harm caused by alcohol in a way that other measures like taxation simply cannot. As such we remain confident that the legal case behind minimum unit pricing is a strong one."

He insisted: " We know from all the evidence that minimum unit pricing will help to save lives, lowering consumption and reducing the damage caused to the most harmful drinkers.

"Every year of delay to the implementation of this policy comes with a human cost of lives lost."

Dr Bennie added: " There is still some way to go in the legal process holding up implementation and even at this stage we would encourage the Scotch Whisky Association to act in the public interest by ending their efforts to delay minimum unit pricing in the courts."

Dr Peter Rice, the chairman of Scottish Health Action on Alcohol Problems (SHAAP), said: " Twenty Scottish people die every week from the effects of alcohol. Much of this comes from the cheapest alcohol.

"As clinicians, we welcome the Advocate General's opinion as a step towards implementing minimum unit pricing as soon as possible. We are confident that Minimum Unit Price has substantial health improvement advantages over other possible price mechanisms and is therefore legal."

Meanwhile Dr Andrew Fraser, the director of public health science at NHS Health Scotland, said: " A minimum unit price for alcohol could save hundreds of lives each year. No other pricing mechanism exists to achieve the same public health benefit, a key factor that will be taken into account by the European Court of Justice before delivering its final judgement."

He added: " We strongly believe that this innovative, evidence-based policy is proportionate to the public health challenge we face in Scotland. It would save lives, reduce alcohol-related harm, and reduce health inequalities in Scotland."

Emily Robinson, deputy chief executive at Alcohol Concern, said: " In Canada, where minimum pricing has been in place, research shows a 10% rise in prices led to a 30% drop in deaths.

"We believe it's time for the global alcohol lobbyists to stop wasting taxpayers' money with legal challenges and accept that legislation has been passed democratically by the Scottish Parliament to introduce minimum unit pricing."

There was also some support for the measure from within the drinks industry, with Alastair Campbell, managing director of Tennent Caledonian Breweries, arguing it " would be a lost opportunity for Scotland" if minimum pricing was not introduced.

He said: " We believe that there is no doubt and plenty of evidence to show that cheap alcohol is a driver of consumption for some people. Minimum unit pricing would be a brave but very useful step in tackling this misuse of alcohol."

The brewing firm has backed minimum pricing since 2011, with Mr Campbell stating: " As always, but particularly in light of today, we encourage the Scottish Government to continue to show leadership. We pledge to support their aims and work with them on a wider strategy."

But one lawyer said if the European Court of Justice followed the Advocate General's opinion, it would "spell the end" for the policy.

Michael Dean, partner and head of EU, competition & regulatory practice with the commercial law firm Maclay Murray & Spens LLP, said: " Should the Advocate General's opinion be followed by the court judgment in some months' time this would spell the end of the use of minimum per unit pricing of alcohol sold in Scotland to influence a reduction in consumption.

"The fact that the challenge was brought by the Scotch Whisky Association does not limit the effects of the challenge; it would apply across the entire alcoholic drinks sector such as spirits, wine, beer, lager and cider. To achieve the laudable health aims, other measures less restrictive of trade must be used."